When manufacturing a semiconductor device, a cleaning process is performed to a semiconductor wafer (referred to as “wafer” below) by using a cleaning liquid, such as a chemical liquid and a deionized water, to remove contaminations adhering to the wafer, such as particles, organic contaminations, and metal impurities. A scrubbing method has been known as such a cleaning process in which a brush is brought into contact with a wafer to scrub the same (see, for example, JP2003-332287A). The scrubbing process using a brush is particularly carried out for cleaning a rear surface of a wafer on which a device is not formed. Another method for cleaning a wafer has been known in which a cleaning liquid is made into liquid droplets with the use of a two-fluid nozzle, and the liquid droplets are sprayed onto the wafer (see, for example, JP2003-197597A).
In these conventional cleaning processes, when a brush is used for cleaning wafers for a plurality of times, the brush is contaminated. Then, the contaminations adhering to the brush adhere again to the wafer, so that the wafer cannot be sufficiently cleaned. In particular, under conditions that patterns of a semiconductor device become finer, the following problem may occur. That is, when a rear surface of a wafer is held by an electrostatic chuck at a dry etching step, for example, unless particles adhering to the rear surface are fully removed, the particles might cause a defocus at a succeeding lithography step.
The object of the present invention is to provide a substrate cleaning apparatus, a substrate cleaning method, and a medium for recording a program used for the method, that are capable of preventing a wafer contamination caused by a contaminated brush.